Develop Reference

AES Decrypt a file in NodeJs

I have a JAVA code that does the AES encryption of excel file on the Windows Operating System. I want to decrypt the same file on the MacOs Operating System using NodeJS. I've written a decrypt function in NodeJs which is giving me the following error
error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt
Here is the JAVA Code
import java.security.Key;
import java.io.OutputStream;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
public class fileEncrypter {
try {
final SecretKeySpec key = new SecretKeySpec("1234".getBytes(), "AES");
final Cipher instance = Cipher.getInstance("AES/ECB/PKCS5Padding");
final BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(name));
final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(name2));
instance.init(1, key);
final byte[] b = new byte[4096];
for (int i = bufferedInputStream.read(b); i > -1; i = bufferedInputStream.read(b)) {
final byte[] update = instance.update(b, 0, I);
bufferedOutputStream.write(update, 0, update.length);
}
bufferedInputStream.close();
final byte[] doFinal = instance.doFinal();
bufferedOutputStream.write(doFinal, 0, doFinal.length);
bufferedOutputStream.flush();
bufferedOutputStream.close();
return "success";
} catch(Exception obj) {
System.err.println("Exception occured while encryption:" + obj);
obj.printStackTrace();
return obj.toString();
}
}
Here is the NodeJs code to decrypt
function Decrypt_AES() {
const ALGORITHM = 'aes-128-ecb';
const ENCRYPTION_KEY = "1234";
var decipher = crypto.createDecipher(ALGORITHM, ENCRYPTION_KEY);
decipher.setAutoPadding(true);
var input = fs.createReadStream('test.enc');
var output = fs.createWriteStream('test_copy.xls');
input.pipe(decipher).pipe(output);
output.on('finish', function () {
console.log('Encrypted file written to disk!');
});
output.on('error', function (e) {
console.log(e);
});
}

I've created some examples in both Java and Node.js that will encrypt and decrypt files. The code will be compatible as long as the same key and IV values are used, that is to say the Node code will decrypt the output from the Java and vice-versa.
Now I'm using text files as input here, but you can use any file type as input.
I've updated to use 128-bit AES in ECB mode.
The Key cannot be "1234" since it must be 128-bits long, so I've used the key given below (16 bytes / 128 bits).
Java
import java.io.*;
import javax.crypto.*;
import java.security.*;
import javax.crypto.spec.*;
public class fileEncrypter {
private static final String key = "0123456789ABDCEF";
public static void main(String[] args)
{
encryptFile(key, "java-input.txt", "java-output.txt");
decryptFile(key, "java-output.txt", "java-decrypted.txt");
}
public static void encryptFile(String secret, String inputFile, String outputFile)
{
try
{
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(secret.getBytes(), "AES"));
byte[] inputData = readFile(inputFile);
byte[] outputData = cipher.doFinal(inputData);
writeToFile(outputFile, outputData);
}
catch (Exception e)
{
System.out.println("Error while encrypting: " + e.toString());
}
}
public static void decryptFile(String secret, String inputFile, String outputFile)
{
try
{
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(secret.getBytes(), "AES"));
byte[] inputData = readFile(inputFile);
byte[] outputData = cipher.doFinal(inputData);
writeToFile(outputFile, outputData);
}
catch (Exception e)
{
System.out.println("Error while decrypting: " + e.toString());
}
}
private static byte[] readFile(String fileName) throws IOException {
byte[] data = new byte[(int) new File(fileName).length()];
DataInputStream dis = new DataInputStream(new FileInputStream(fileName));
dis.readFully(data);
dis.close();
return data;
}
private static void writeToFile(String fileName, byte[] data) throws IOException {
final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(fileName));
bufferedOutputStream.write(data, 0, data.length);
bufferedOutputStream.close();
}
}
Node.js
const crypto = require("crypto");
const Algorithm = "aes-128-ecb";
const fs = require("fs");
function encryptFile(key, inputFile, outputFile) {
const inputData = fs.readFileSync(inputFile);
const cipher = crypto.createCipheriv(Algorithm, key, Buffer.alloc(0));
const output = Buffer.concat([cipher.update(inputData) , cipher.final()]);
fs.writeFileSync(outputFile, output);
}
function decryptFile(key, inputFile, outputFile) {
const inputData = fs.readFileSync(inputFile);
const cipher = crypto.createDecipheriv(Algorithm, key, Buffer.alloc(0));
const output = Buffer.concat([cipher.update(inputData) , cipher.final()]);
fs.writeFileSync(outputFile, output);
}
const KEY = Buffer.from("0123456789ABDCEF", "utf8");
encryptFile(KEY, "node-input.txt", "node-output.txt");
decryptFile(KEY, "node-output.txt", "node-decrypted.txt");

I have solved this problem with the help of Terry Lennox. A big thanks to him first.
First Error:
error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt
This was a padding issue, By default, nodeJs uses PKCS padding so I had to set auto padding to false by using decipher.setAutoPadding(false);
This solved the first error
Secondly, I was using crypto.createDecipher(ALGORITHM, ENCRYPTION_KEY) which processes the key before using it. To solve this I changed the function to
crypto.createDecipheriv(ALGORITHM, ENCRYPTION_KEY, null)
This was giving me error as we cannot pass null in place of IV value.
Since ECB does not require any IV, and we cannot pass null in place of IV I had to set my IV value to this Buffer.alloc(0)
This is the code that worked for me
function Decrypt_AES() {
const ALGORITHM = 'aes-128-ecb';
const key = "1234";
const ENCRYPTION_KEY = key;
var IV = Buffer.alloc(0);
var decipher = crypto.createDecipheriv(ALGORITHM, ENCRYPTION_KEY, IV);
decipher.setAutoPadding(false);
var input = fs.createReadStream('test.enc');
var output = fs.createWriteStream('test_copy.xls');
input.pipe(decipher).pipe(output);
output.on('finish', function () {
console.log('Decrypted file written to disk!');
});
output.on('error', function (e) {
console.log(e);
});
}

How to fix my Encryption/Decryption code to go into a text file

Every time I run the code it says that the deciphered text file can't be found. It works without the code I can't modify (because my teacher wrote that we can't) but with it, it refuses to work. My teacher won't help me and no one else in my class knows how to code with the cipher class. I have used the PrintWriter class, and pretty much everything else. So I don't know what to do. Someone please help me figure out how to make it work.
package Crypto;
import java.util.Scanner;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.FileWriter;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
public class Crypto {
public static void main(String[] args) throws IOException {
try {
String key = "B1LLYB0B";
FileInputStream One = new FileInputStream("CryptoPlaintext.txt");
FileOutputStream Two = new FileOutputStream("CryptoCiphertext.txt");
encrypt(key, One, Two);
Two.flush();
Two.close();
FileInputStream One2 = new FileInputStream("CryptoCiphertext.txt");
FileOutputStream Two2 = new FileOutputStream("CryptoDeciphered.txt");
Two2.write(key.getBytes());
Two2.close();
decrypt(key, One2, Two2);
} catch (Throwable e) {
e.printStackTrace();
}
}
public static void encrypt(String key, InputStream is, OutputStream os) throws Throwable {
encryptOrDecrypt(key, Cipher.ENCRYPT_MODE, is, os);
}
public static void decrypt(String key, InputStream is, OutputStream os) throws Throwable {
encryptOrDecrypt(key, Cipher.DECRYPT_MODE, is, os);
}
public static void encryptOrDecrypt(String key, int mode, InputStream is, OutputStream os) throws Throwable {
DESKeySpec dks = new DESKeySpec(key.getBytes());
SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
SecretKey desKey = skf.generateSecret(dks);
Cipher cipher = Cipher.getInstance("DES");
if (mode == Cipher.ENCRYPT_MODE) {
cipher.init(Cipher.ENCRYPT_MODE, desKey);
CipherInputStream cis = new CipherInputStream(is, cipher);
doCopy(cis, os);
} else if (mode == Cipher.DECRYPT_MODE) {
cipher.init(Cipher.DECRYPT_MODE, desKey);
CipherOutputStream cos = new CipherOutputStream(os, cipher);
doCopy(is, cos);
}
}
public static void doCopy(InputStream is, OutputStream os) throws IOException {
byte[] bytes = new byte[64];
int numBytes;
while ((numBytes = is.read(bytes)) != -1) {
os.write(bytes, 0, numBytes);
}
os.flush();
os.close();
is.close();
// =============================== DO NOT MODIFY ANY CODE BELOW HERE ===============================
// Compare the files
System.out.println(compareFiles() ? "The files are identical!" : "The files are NOT identical.");
}
/**
* Compares the Plaintext file with the Deciphered file.
*
* #return true if files match, false if they do not
*/
public static boolean compareFiles() throws IOException
{
Scanner pt = new Scanner(new File("CryptoPlaintext.txt")); // Open the plaintext file
Scanner dc = new Scanner(new File("CryptoDeciphered.txt")); // Open the deciphered file
// Read through the files and compare them record by record.
// If any of the records do not match, the files are not identical.
while(pt.hasNextLine() && dc.hasNextLine())
if(!pt.nextLine().equals(dc.nextLine())) return false;
// If we have any records left over, then the files are not identical.
if(pt.hasNextLine() || dc.hasNextLine()) return false;
// The files are identical.
return true;
}
}

Why the error occurs:
You invoke the method compareFiles in your copy method, which is called to copy the encrypted content of the plaintext file to the cipher text file. When this call occurs the file containing the decrypted cipher text doesn't exist but is required by the compareFiles method resulting in your exception.
How to improve your code:
you don't need the statement Two2.write(key.getBytes())
use the try-with-resource statement to automatically flush and close your streams
the standard library provides methods to copy data from a path to a stream and vice versa. Have a look at Files.copy(...) or Guava's ByteStreams.copy(...)
change your methods' throws clause, throws Throwable is just bad design to get rid of proper exception handling, if you are struggling with InvalidKeyException, NoSuchAlgorithmException, etc, catch these when you create your cipher and rethrow e.g. IllegalArgumentException or a custom exception
Here is an example how to implement it:
public class Crypto
{
public static void main(String[] args)
{
byte[] key = "B1LLYB0B".getBytes(StandardCharsets.UTF_8);
Path plaintext = Paths.get("CryptoPlaintext.txt");
Path ciphertext = plaintext.resolveSibling("CryptoCiphertext.txt");
Path decrypted = ciphertext.resolveSibling("CryptoDeciphered.txt");
try
{
// Encrypt plaintext.
try (OutputStream os = encrypt(key, Files.newOutputStream(ciphertext)))
{
Files.copy(plaintext, os);
}
// Decrypt ciphertext.
try (InputStream is = decrypt(key, Files.newInputStream(ciphertext)))
{
Files.copy(is, decrypted);
}
// TODO Compare plaintext and decrypted ciphertext.
}
catch (IOException e)
{
e.printStackTrace(); // TODO Handle exception properly.
}
}
private static OutputStream encrypt(byte[] key, OutputStream os)
{
return new CipherOutputStream(os, getCipherInstance(key, Cipher.ENCRYPT_MODE));
}
private static InputStream decrypt(byte[] key, InputStream is)
{
return new CipherInputStream(is, getCipherInstance(key, Cipher.DECRYPT_MODE));
}
private static Cipher getCipherInstance(byte[] key, int mode)
{
// TODO Implement and return the desired cipher.
}
}
By the way: Your teacher doesn't close his scanners in compareFiles() resulting in a resource leak.

javax.crypto.BadPaddingException: Given final block not properly padded after patching WebSphere

Well, this is not a new program and I haven't done any changes with problem parts.
My system admin has just patched the IBM WebSphere Application Server from 8.5.0.1 to 8.5.5.4.
I have encrypted numbers of files in the past. But after the upgrade has completed, I can't decrypt these files any more.
I am sure I am using the same method and key as they are all hard-coded in my program. And I haven't changed any related codes.
Here is the error.
javax.crypto.BadPaddingException: Given final block not properly padded
at com.ibm.crypto.provider.AESCipher.engineDoFinal(Unknown Source)
at com.ibm.crypto.provider.AESCipher.engineDoFinal(Unknown Source)
at javax.crypto.Cipher.doFinal(Unknown Source)
at com.xxx.framework.core.common.util.CipherUtil.crypt(CipherUtil.java:175)
at com.xxx.framework.core.common.util.CipherUtil.decrypt(CipherUtil.java:102)
at com.xxx.framework.core.common.util.ZipCipherUtil.decryptUnzip(ZipCipherUtil.java:84)
at xxx(xxx.java:2894)
at xxx(xxx.java:748)
at xxx(xxx.java:727)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:611)
at yyy(ActionProxy.java:54)
I have deleted some parts as there are some sensitive business information
And this is the code
CipherUtil.java
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.GeneralSecurityException;
import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
public class CipherUtil {
private static String type = "AES";
private static final String HEXES = "0123456789ABCDEF";
public void encrypt(String srcFile, String destFile, String privateKey) throws GeneralSecurityException, IOException {
Key key = getKey(privateKey);
Cipher cipher = Cipher.getInstance(type + "/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, key);
FileInputStream fis = null;
FileOutputStream fos = null;
try {
fis = new FileInputStream(srcFile);
fos = new FileOutputStream(mkdirFiles(destFile));
crypt(fis, fos, cipher);
} catch (FileNotFoundException e) {
e.printStackTrace();
throw e;
} catch (IOException e) {
e.printStackTrace();
throw e;
} finally {
if (fis != null) {
fis.close();
}
if (fos != null) {
fos.close();
}
}
}
public void decrypt(String srcFile, String destFile, String privateKey) throws GeneralSecurityException, IOException {
Key key = getKey(privateKey);
Cipher cipher = Cipher.getInstance(type + "/ECB/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, key);
FileInputStream fis = null;
FileOutputStream fos = null;
try {
fis = new FileInputStream(srcFile);
fos = new FileOutputStream(mkdirFiles(destFile));
crypt(fis, fos, cipher);
} catch (FileNotFoundException e) {
e.printStackTrace();
throw e;
} catch (IOException e) {
e.printStackTrace();
throw e;
} finally {
if (fis != null) {
fis.close();
}
if (fos != null) {
fos.close();
}
}
}
private static Key getKey(String secret) throws GeneralSecurityException {
KeyGenerator kgen = KeyGenerator.getInstance(type);
kgen.init(128, new SecureRandom(secret.getBytes()));
SecretKey secretKey = kgen.generateKey();
return secretKey;
}
private static void crypt(InputStream in, OutputStream out, Cipher cipher) throws IOException, GeneralSecurityException {
int blockSize = cipher.getBlockSize() * 1000;
int outputSize = cipher.getOutputSize(blockSize);
byte[] inBytes = new byte[blockSize];
byte[] outBytes = new byte[outputSize];
int inLength = 0;
boolean more = true;
while (more) {
inLength = in.read(inBytes);
if (inLength == blockSize) {
int outLength = cipher.update(inBytes, 0, blockSize, outBytes);
out.write(outBytes, 0, outLength);
} else {
more = false;
}
}
if (inLength > 0)
outBytes = cipher.doFinal(inBytes, 0, inLength);
else
outBytes = cipher.doFinal();
out.write(outBytes);
}
public String encryptString(String srcString, String keyString) throws GeneralSecurityException {
Key key = getKey(keyString);
Cipher cipher = Cipher.getInstance(type + "/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] coded = cipher.doFinal(srcString.getBytes());
return byteArrayToHexString(coded);
}
public String decryptString(String srcString, String keyString) throws GeneralSecurityException {
Key key = getKey(keyString);
Cipher cipher = Cipher.getInstance(type + "/ECB/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] decoded = cipher.doFinal(hexStringToByteArray(srcString));
return new String(decoded);
}
private String byteArrayToHexString(byte[] raw)
{
if (raw == null)
{
return null;
}
final StringBuilder hex = new StringBuilder(2 * raw.length);
for (final byte b : raw)
{
hex.append(HEXES.charAt((b & 0xF0) >> 4))
.append(HEXES.charAt((b & 0x0F)));
}
return hex.toString();
}
public static byte[] hexStringToByteArray(String s) {
if (s == null || (s.length() % 2) == 1)
{
throw new IllegalArgumentException();
}
final char[] chars = s.toCharArray();
final int len = chars.length;
final byte [] data = new byte [len / 2];
for (int i=0; i<len; i+=2)
{
data[i / 2] = (byte) ((Character.digit (chars[i], 16) << 4) + Character.digit (chars[i + 1], 16));
}
return data;
}
}
Although I have mentioned "files", this method only treat the files as binary string to encrypt.
As I have DEV and UAT environment to test (DEV=8.5.5.4, UAT=8.5.0.1), I have tried to put the old encrypted files on DEV to the UAT. And they can decrypted under UAT.
Also I have tried to encrypt a new file under DEV and decrypt it, it is ok.
Is there anything I need to call my system admin to do?
I am only a programmer and I am not very skillful in server setup.
P.S. If there is anything to check, I am able to go into the WebSphere admin panel with admin right.
P.S.2. These codes are not written by me. Don't ask me what is the reason of these coding. By the way I have checked the codes and I can't find any issue with these codes, except some security worries but I am not sure.

Not sure if it is your problem or not, but this block:
while (more) {
inLength = in.read(inBytes);
if (inLength == blockSize) {
int outLength = cipher.update(inBytes, 0, blockSize, outBytes);
out.write(outBytes, 0, outLength);
} else {
more = false;
}
}
is at least in principle incorrect. The in.read() could theoretically read less than the block length before reaching the end of file. The EOF condition is that in.read() returns -1. Maybe the update to the operating system has caused the FileInputStream to occasionally interrupt the read? In this case you will for the first time fall into the the inLength > 0 block of your code and try to decrypt a partial block which will definitely give the wrong result.
You can also temporarily disable PKCS5Padding by using NoPadding and see what the output of the encryption is.

Transfer Multiple File problems via socket

Server side:
public class Server
{
public static final String ALGORITHM = "RSA";
public static final String PRIVATE_KEY_FILE = "C:/Users/mrarsenal10/Desktop/server/key/private.key";
public static final String PUBLIC_KEY_FILE = "C:/Users/mrarsenal10/Desktop/server/key/public.key";
public static void generateKey()
{
try
{
final KeyPairGenerator keyGen = KeyPairGenerator.getInstance(ALGORITHM);
keyGen.initialize(1024);
final KeyPair key = keyGen.generateKeyPair();
File privateKeyFile = new File(PRIVATE_KEY_FILE);
File publicKeyFile = new File(PUBLIC_KEY_FILE);
// Create files to store public and private key
if (privateKeyFile.getParentFile() != null) {
privateKeyFile.getParentFile().mkdirs();
}
privateKeyFile.createNewFile();
if (publicKeyFile.getParentFile() != null) {
publicKeyFile.getParentFile().mkdirs();
}
publicKeyFile.createNewFile();
// Saving the Public key in a file
ObjectOutputStream publicKeyOS = new ObjectOutputStream(
new FileOutputStream(publicKeyFile));
publicKeyOS.writeObject(key.getPublic());
publicKeyOS.close();
// Saving the Private key in a file
ObjectOutputStream privateKeyOS = new ObjectOutputStream(
new FileOutputStream(privateKeyFile));
privateKeyOS.writeObject(key.getPrivate());
privateKeyOS.close();
}catch (Exception e)
{
e.printStackTrace();
}
}
public static boolean areKeysPresent()
{
File privateKey = new File(PRIVATE_KEY_FILE);
File publicKey = new File(PUBLIC_KEY_FILE);
if (privateKey.exists() && publicKey.exists())
{
return true;
}
return false;
}
public static String decrypt(byte[] text, PrivateKey key) { // giải mã
byte[] dectyptedText = null;
try {
// get an RSA cipher object and print the provider
final Cipher cipher = Cipher.getInstance(ALGORITHM);
// decrypt the text using the private key
cipher.init(Cipher.DECRYPT_MODE, key);
dectyptedText = cipher.doFinal(text);
} catch (Exception ex) {
ex.printStackTrace();
}
return new String(dectyptedText);
}
static void sendFile(Socket sock, String fName) throws FileNotFoundException, IOException
{
File transferFile = new File (fName);
byte [] bytearray = new byte [(int)transferFile.length()];
FileInputStream fin = new FileInputStream(transferFile);
BufferedInputStream bin = new BufferedInputStream(fin);
bin.read(bytearray,0,bytearray.length); // luu vao bytearray
OutputStream os = sock.getOutputStream(); // goi outputstream de
System.out.println("Sending Files...");
os.write(bytearray,0,bytearray.length);
os.flush();
}
public static void main(String[] args) throws IOException, ClassNotFoundException {
if (!areKeysPresent()) {
generateKey();
}
ServerSocket serverSocket = new ServerSocket(15124);
Socket sock = serverSocket.accept();
sendFile(sock, PUBLIC_KEY_FILE);
sendFile(sock, "lich.txt");
sock.close();
}
}
Client side:
public class Client
{
public static final String ALGORITHM = "RSA";
public static final String PUBLIC_KEY_FILE = "C:/Users/mrarsenal10/Desktop/Client/public.key";
static void recvFile(Socket sock, String fName) throws FileNotFoundException, IOException
{
int filesize=1022386;
int bytesRead;
int currentTot = 0;
byte [] bytearray = new byte [filesize];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream(fName);
BufferedOutputStream bos = new BufferedOutputStream(fos);
bytesRead = is.read(bytearray,0,bytearray.length);
currentTot = bytesRead;
do {
bytesRead = is.read(bytearray, currentTot, (bytearray.length-currentTot));
if(bytesRead >= 0) currentTot += bytesRead; }
while(bytesRead > -1);
bos.write(bytearray, 0 , currentTot);
bos.flush();
bos.close();
}
public static byte[] encrypt(String text, PublicKey key) {
byte[] cipherText = null;
try {
// get an RSA cipher object and print the provider
final Cipher cipher = Cipher.getInstance(ALGORITHM);
// encrypt the plain text using the public key
cipher.init(Cipher.ENCRYPT_MODE, key);
cipherText = cipher.doFinal(text.getBytes());
} catch (Exception e) {
e.printStackTrace();
}
return cipherText;
}
public static void main(String[] args) throws IOException, ClassNotFoundException {
Socket sock = new Socket("127.0.0.1",15124);
recvFile(sock, "public.key");
recvFile(sock, "lich.txt");
sock.close();
}
}
My problem is here i just can send "public.key" or "lich.txt" from server to client, now i want to send both "public.key" and "lich.txt". Thank for your help.

The problem is with the overall design of both the Server and the Client. On the server side it is sending two different files, but on the Client side it is just a stream of data. There is no distinction between one byte representing data from one file vs the next. So what is probably happening is you are calling recvFile, which receives ALL the data from BOTH files sent by the server. After sending the data, the server closes the connection. (You do this explicitly.) So now, on the client side, you have an invalid socket. However, you try to call recvFile again with the socket thinking that represents the second file. This will lead to the SocketException or more likely OutOfBoundsException you are seeing.
To fix this, you need to add more hand-shaking between the Server and Client. The simplest would be a delimiter representing the end of a file. A better approach would be to append a known-size header to the front of every "message" (aka file) before sending any data which lets the client know the size of the file. Then once the client receives the header it knows exactly how many bytes to read.
For now, to prevent the crash change you're recvFile method to something like this:
byte[] bytearray = new byte[4096];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream(fName);
int bytesRead;
while ((bytesRead = is.read(bytearray)) >= 0) {
if (bytesRead > 0) {
fos.write(bytearray, 0, bytesRead);
}
}
fos.flush();
fos.close();

In AES decryption, "Given final block not properly padded" occurred

I'm doing a simple encryption file transfer system and now stopped by a run time exception:
Exception in thread "main" javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:811)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:676)
at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:313)
at javax.crypto.Cipher.doFinal(Cipher.java:2087)
at ftpclient.FTPClient.main(FTPClient.java:82)
I tried to debug my code using a string to encrypt and decrypt with the same key and it works. However, when I tried to transfer stream from the file, this exception always comes.
Here are the codes of both sides. At first they will exchange symmetric key (AES key) via RSA and then transfer large files via AES encryption. We can focus on the last part of each code where the files are encrypted and decrypted by AES key.
Server Side:
package ftpserver;
import java.io.*;
import java.net.*;
import javax.crypto.*;
import java.security.*;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
/**
*
* #author Han
*/
public class FTPServer {
public static void main(String[] args) throws Exception {
//generate symmetric key and initialize cipher for AES
SecretKey skey = null;
Cipher aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
KeyGenerator kg = KeyGenerator.getInstance("AES");
kg.init(128);
skey = kg.generateKey();
//get public key of the receive side
final String PUBLIC_KEY_PATH = "key_b.public";
PublicKey publickey = null;
try {
FileInputStream fis;
fis = new FileInputStream(PUBLIC_KEY_PATH);
ObjectInputStream oin = new ObjectInputStream(fis);
publickey = (PublicKey) oin.readObject();
oin.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
};
//encrypte symmetric key with own private key and send out
Cipher rsa = Cipher.getInstance("RSA");
rsa.init(Cipher.ENCRYPT_MODE, publickey);
byte cipherSKey[] = rsa.doFinal(skey.getEncoded());
//System.out.println(skey); //debug
//create tcp server socket
ServerSocket tcp = new ServerSocket(2000);
Socket client = tcp.accept();
//get input&output stream from the TCP connection
InputStream in = client.getInputStream();
OutputStream out = client.getOutputStream();
//generate a file input stream to get stream from file
File sentFile = new File("F:\\test.txt");
FileInputStream fin = new FileInputStream(sentFile);
//send encrypted symmetric key first
out.write("Symmetric Key:\r\n".getBytes());
out.write(cipherSKey);
DataInputStream din = new DataInputStream(in);
while(true)
{
if(din.readLine().equals("Received."))
{
System.out.println("Send key successfully.");
break;
}
};
//send files
int count;
byte[] bytearray = new byte[8192];
byte[] cipherbuffer;
while((count = fin.read(bytearray))>0)
{
cipherbuffer = Base64.encodeBase64(aes.doFinal(bytearray));
out.write(cipherbuffer,0,cipherbuffer.length);
System.out.println(count+" bytes have been sent.");
};
out.flush();
out.close();
client.close();
}
}
Client Side:
package ftpclient;
import java.io.*;
import java.net.*;
import java.security.PrivateKey;
import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
/**
*
* #author Han
*/
public class FTPClient {
public static void main(String[] args) throws Exception
{
//get the private key of this side
final String PUBLIC_KEY_PATH = "key_b.privat";
PrivateKey privatkey = null;
try {
FileInputStream fis;
fis = new FileInputStream(PUBLIC_KEY_PATH);
ObjectInputStream oin = new ObjectInputStream(fis);
privatkey = (PrivateKey) oin.readObject();
oin.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
};
Cipher rsa = Cipher.getInstance("RSA");
rsa.init(Cipher.DECRYPT_MODE, privatkey);
//create tcp client socket
Socket tcp = new Socket("192.168.1.185",2000);
InputStream in = tcp.getInputStream();
OutputStream out = tcp.getOutputStream();
DataInputStream din = new DataInputStream(in);
//receive symmetric key from server
byte keybuffer[] = new byte[128];
SecretKey skey = null;
while(true)
{
if(din.readLine().equals("Symmetric Key:"))
{
System.out.println("Start to receiving key...");
in.read(keybuffer);
byte[] skeycode = rsa.doFinal(keybuffer);
skey = new SecretKeySpec(skeycode, 0, skeycode.length, "AES");
out.write("Received.\r\n".getBytes());
break;
}
};
//create cipher for symmetric decryption
Cipher aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
aes.init(Cipher.DECRYPT_MODE, skey);
//System.out.println(skey); //debug
//create file stream
FileOutputStream fos = new FileOutputStream("E:\\test_cp.txt");
int count;
int i = 0;
byte[] bytearray = new byte[8192];
byte[] buffer;
while((count = in.read(bytearray)) > 0)
{
buffer = (aes.doFinal(Base64.decodeBase64(bytearray)));
fos.write(buffer,0,buffer.length);
i +=count;
System.out.println(i+" bytes have been received.");
};
fos.flush();
fos.close();
in.close();
tcp.close();
System.out.println("File Transfer completed");
}
}

you are calling doFinal multiple times. or at least trying to.
when you read data, not all data arrives or is read into the buffer at once. so you decrypt some and then read again. that is all ok.
but when you do that, you are calling doFinal each time, instead of update. this is wrong and is the cause of the error. instead, replace doFinal with update and then add an extra doFinal once you have finished reading all data (there is a doFinal() that takes no arguments for exactly this reason).
see http://docs.oracle.com/javase/7/docs/api/javax/crypto/Cipher.html
also see http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Electronic_codebook_.28ECB.29 for why ecb mode is often not a good idea (look at the penguin pictures).